DE102022112383A1 - Process for marking a component - Google Patents

Abstract

The invention relates to a method for marking a component (1) by applying a marking (3) to a surface (2) of the component (1), comprising the following steps: providing a powder; preparing a green compact from the powder by filling the powder in a mold and pressing the filled powder; applying a multidimensional code as a marking (3) in/on the surface (2) of the green body; sintering the green body; optionally hardening the sintered green compact; wherein the multi-dimensional code is generated in a single step on a pressing surface of the green compact.

Description

The invention relates to a method for marking a component by applying a marking to a surface of the component, comprising the following steps: providing a powder; preparing a green body from the powder by filling the powder in a mold and pressing the filled powder; application of a multidimensional code as a marking in the surface of the green body; sintering the green body; optionally hardening the sintered green compact.

The invention further relates to a component produced from a sintered material using a powder-metallurgical process, with a multi-dimensional code being arranged on a surface of the component.

It is already known from the prior art that sintered products are marked or coded by applying a code to the green compact. Thus, JPH-05185714 A describes a marking method for a powder-sintered product, comprising: injection molding a mixture of metal or ceramic powder and an organic binder; applying a laser mark of letters to the green body; debinding of the green body; and sintering the green body.

It is considered problematic that cavities that are essentially as large as a point in the code cause reading errors in a code reader.

To avoid this problem, the DE 11 2018 003 673 T5 proposes a laser marking method for a powder compact containing metal powder, comprising a first step of scanning laser light having a first power which is weaker over a predetermined area in a surface of the powder compact to melt and smooth the interior of the predetermined area, and a second step scanning laser light with a second power that is larger to form a spot formed of a pit having a predetermined depth at a predetermined location in the predetermined area. This publication also describes a sintered product obtained by sintering a metal powder-containing powder compact, comprising a two-dimensional code having a plurality of dots applied by laser marking on a surface of the powder compact, with the oxygen content at a surface of the sintered product in the vicinity of the dots is 2% by weight or less.

The object of the present invention was to provide a simple way of tracing a component produced by powder metallurgy.

This object is achieved by the method mentioned at the outset, in which it is provided that the multidimensional code is generated in a single step on a pressing surface of the green body.

The object of the invention is also achieved with the component mentioned at the outset, in which the multidimensional code has a cell contrast of at least 70%.

The advantage here is that compared to the method according to the above DE 11 2018 003 673 T5 there is no need to level the surface to be marked. The leveling process closes the pores, which means that the marking itself takes longer because more material has to be melted with the laser. Surprisingly, the leader in this one DE 11 2018 003 673 T5 described disadvantage in the laser marking of green compacts does not make the code unreadable, although such codes are usually generated with closely spaced dots. The method according to the invention leads to a component whose marking has the abovementioned luminance levels. In this way, the marking fits better into the overall appearance of the component without appearing too strongly contrasting in the foreground.

According to one embodiment variant of the invention, the multidimensional code is preferably generated by means of electromagnetic radiation, in particular bundled light radiation. Compared to other marking methods, the penetration depth of the marking can be determined relatively easily in order to be able to adjust the luminance of the code accordingly. When the mark is formed to a relatively large depth, it appears lighter on the sintered component. In addition, compared to other methods of code generation, the code can be introduced into the material relatively gently.

According to a further embodiment variant of the invention, a data matrix code is preferably produced in the surface of the component for marking the component. It is thus possible to place a relatively large amount of information on a relatively small area, although this code is still simple in design compared to other two-dimensional codes, so that a reduction in contrast does not affect the readout accuracy of the code or does not interfere with it. This in turn supports the marking of a green body in just one step without prior preparation of the surface to be marked.

For rapid marking of the component in series production, according to a further embodiment variant, provision can be made for the multidimensional code to be generated on an area of at most 400 mm ² .

To further improve the aforementioned effects, according to another embodiment of the invention, the multidimensional code can be formed at least in regions at a depth of between 25 μm and 50 μm, measured from the surface of the component. At a depth of more than 50 µm, the sharpness of the introduced point would be impaired too much, since more material around the point itself is heated and thus possibly sintered or even melted during marking.

For a better understanding of the invention, it is explained in more detail with reference to the following figures.

• 1 ein gesintertes Bauteil mit einer Markierung;
• 2 ein Gefügebild der markierten Oberfläche des Bauteils;
• 3 den Vorgang der Markierung des Bauteils.

They each show in a greatly simplified, schematic representation:

• 1 a sintered component with a mark;
• 2 a micrograph of the marked surface of the component;
• 3 the process of marking the component.

As an introduction, it should be noted that in the differently described embodiments, the same parts are provided with the same reference numbers or the same component designations, it being possible for the disclosures contained throughout the description to be applied to the same parts with the same reference numbers or the same component designations. The position information selected in the description, such as top, bottom, side, etc., is related to the figure directly described and shown and these position information are to be transferred to the new position in the event of a change of position.

In 1 a component 1 is shown. The component 1 is a gear. However, it should be noted that the illustrated shape of the component 1 is only to be understood as representative of other components 1 if these are components 1 that are produced using a powder-metallurgical process. The invention is therefore not limited to gears.

The component 1 carries a marking 3 on a surface 2, for example an end face. The marking 3 is a multidimensional code, ie no marking 3 with alphanumeric characters (letters, numbers, etc.). The marking 3 consists in particular of lines and/or dots (ideally rectangles and squares).

The multi-dimensional code is preferably a two-dimensional code, such as a matrix code, e.g., a QR code. In particular, according to an embodiment variant of the invention, the code is a so-called data matrix code. Since these codes are known per se, no further explanation is necessary. The person skilled in the art is referred to the relevant literature. For example, the DataMatrix code is defined in the ISO/IEC 16022:2006 standard.

The marking 3 can also be formed by a three-dimensional code, such as a three-dimensional QR code in particular, by causing material changes in the component 1 when generating the code at a distance from the surface 2 within the component 1 of the desired coding.

As already mentioned, the component 1 is produced using a powder-metallurgical process. A corresponding (metallic) sinter powder is provided for this purpose, such as a commercially available sintered steel powder. A so-called green compact is then produced from this powder.

A green compact is understood to mean a molded part pressed from a sinter powder in the stage immediately after the pressing of the sinter powder and before sintering, as this corresponds to general technical usage. The green body is therefore a blank from which the (finished) component 1 is produced by sintering.

The green compact can be produced, for example, in a die with a mold cavity. The mold cavity generally has the negative shape of the subsequent component 1 together with the press die(s). “In general” means that details of the component 1 that cannot be produced by pressing, such as some undercuts, etc., can be produced later.

After the powder has been pressed into a green body, it is ejected from the die and fed to single- or multi-stage sintering. Depending on the powder used, sintering can take place, for example, at a temperature between 600° C. and 1300° C.

Subsequent to sintering, the sintered green body can be reworked, e.g. calibrated and/or hardened.

For better traceability or assignability of a specific component 1 is now the Mark 3 provided in the form of a multidimensional code. This code can contain information on the production date, the production time, the production site, the batch, etc. Based on this data, the component 1 can be clearly assigned even after a long period of use. For this purpose, the code can be read with a suitable reading device, such as a scanner or a camera, etc., and the corresponding readable alphanumeric characters can then be generated from this data. Readers per se are known from the prior art.

The code is introduced into the green compact. For this purpose, the marking can take place before or after the green compact is ejected from the die or the shaping tool. The code is thus introduced into the, in particular untreated, pressing surface, ie the surface that the green compact has immediately after pressing. There is no leveling of the surface 2 on or into which the marking 3 is applied or incorporated. The green compact has a green compact density on the surface of between 6.6 g/cm ³ and 7.3 g/cm ³ .

The code is thus generated in a single processing step on or in the untreated green compact surface.

In principle, the multidimensional code can be generated with any suitable tool. However, electromagnetic radiation is preferably used to generate the code on or in the surface 2 of the component 1, particularly preferably a laser.

For the reasons mentioned above, it is advantageous according to a further embodiment if the two-dimensional code is formed at least in regions with a (maximum) depth 4 of between 25 μm and 50 μm, measured from the surface 2 of the component 1. This shows the 2 , which is a micrograph of the component 1 after 1 in the area marked 3. “At a depth 4” means that the component 1 has a marking 3 that has code components that extend from the surface to the depth 4 mentioned. In the case of electromagnetic radiation, in particular laser light, for producing the code, one can also speak of burn-in depth.

It is therefore not necessary for the entire marking 3 or the entire code to extend down to this depth 4 . However, an average depth 4 can be selected from a range of 20 μm to 40 μm, for example from a range of 25 μm to 30 μm. The mean depth 4 is calculated as the arithmetic mean of the maximum depths 4 of ten code components (bars and/or dots).

In 3 the generation of the marking is shown in simplified form. Laser light 6 is radiated into the green compact by a laser 5, as a result of which the pressed powder is melted in this area and partially evaporated. This metal vapor leaves a depression 7 (hole) in the green part, which forms part of the code to be introduced. How out 3 As can be seen, the depression 7 surrounds a molten pool which solidifies again after marking. The depth 4 is thus smaller than the depth to which the pressed powder is melted. In addition, the depression 7 has an edge with a material upset 8 that contributes to the appearance of the code, ie the marking 3 on the component 1 .

The material upset can be generated with a height 9, which is between 20 microns and 40 microns.

With the method according to the invention, a component 1 (also referred to as a sintered component) produced using a powder-metallurgical method can be produced, which has a marking 3 from a code, the code, i.e. the components of the code (bars and/or dots) having a Cell contrast of at least 70% (ISO/IEC TR 29158-2011-10), in particular a cell contrast between 70% and 95% (ISO/IEC TR 29158-2011-10). The cell contrast is the difference between the mean value of the light and dark areas divided by the mean value of the light area.

The Michelson contrast Km is calculated according to Km = (Lmax-Lmin)/(Lmax+Lmin).

The exemplary embodiments show or describe possible embodiment variants of the component 1 or the marking 3, it being noted at this point that combinations of the individual embodiment variants with one another are also possible.

Finally, for the sake of clarity, it should be pointed out that the component 1 and the marking 3 are not necessarily shown to scale for a better understanding of the structure.

Reference List

1

component

2

surface

3

mark

4

depth

5

laser

6

laser light

7

deepening

8th

material buckling

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 112018003673 T5 [0005, 0009]

Claims (6)

Method for marking a component (1) by applying a marking (3) to a surface (2) of the component (1), comprising the following steps: - providing a powder; - preparing a green compact from the powder by filling the powder in a mold and pressing the filled powder; - Application of a multidimensional code as a marking (3) in / on the surface (2) of the green body; - sintering of the green body; - Optional hardening of the sintered green compact; characterized in that the multi-dimensional code is generated in a single step on a pressing surface of the green body. procedure after claim 1 , characterized in that the multidimensional code is generated by means of electromagnetic radiation. procedure after claim 1 or 2 , characterized in that for marking the component (1) a data matrix code is produced in/on the surface (2) of the component (1). Procedure according to one of Claims 1 until 3 , characterized in that the multidimensional code is generated on an area of at most 100 mm ² . Procedure according to one of Claims 1 until 4 , characterized in that the multi-dimensional code is formed at least in regions at a depth (4) between 25 µm and 50 µm, measured from the surface (2) of the component (1). Component (1) produced from a sintered material using a powder metallurgy process, a multidimensional code being arranged in a surface (2) of the component (1), characterized in that the two-dimensional code has a cell contrast of at least 70%.

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